Пример #1
0
func Polygon(g *geos.Geos, nodes []element.Node) (*geos.Geom, error) {
	nodes = unduplicateNodes(nodes)
	if len(nodes) < 4 {
		return nil, ErrorNoRing
	}

	coordSeq, err := g.CreateCoordSeq(uint32(len(nodes)), 2)
	if err != nil {
		return nil, err
	}

	// coordSeq inherited by LinearRing, no destroy
	for i, nd := range nodes {
		err := coordSeq.SetXY(g, uint32(i), nd.Long, nd.Lat)
		if err != nil {
			return nil, err
		}
	}
	ring, err := coordSeq.AsLinearRing(g)
	if err != nil {
		// coordSeq gets Destroy by GEOS
		return nil, err
	}
	// ring inherited by Polygon, no destroy

	geom := g.Polygon(ring, nil)
	if geom == nil {
		g.Destroy(ring)
		return nil, errors.New("unable to create polygon")
	}
	g.DestroyLater(geom)
	return geom, nil
}
Пример #2
0
func Point(g *geos.Geos, node element.Node) (*geos.Geom, error) {
	geom := g.Point(node.Long, node.Lat)
	if geom == nil {
		return nil, NewGeomError("couldn't create point", 1)
	}
	g.DestroyLater(geom)
	return geom, nil
}
Пример #3
0
// mergeGeometries
func mergeGeometries(g *geos.Geos, geoms []*geos.Geom, geomType string) []*geos.Geom {
	// intersections from multiple sub-polygons
	// try to merge them back to a single geometry
	if strings.HasSuffix(geomType, "Polygon") {
		polygons := flattenPolygons(g, geoms)
		polygon := g.UnionPolygons(polygons)
		if polygon == nil {
			return nil
		}
		g.DestroyLater(polygon)
		return []*geos.Geom{polygon}
	} else if strings.HasSuffix(geomType, "LineString") {
		linestrings := flattenLineStrings(g, geoms)
		linestrings = filterInvalidLineStrings(g, linestrings)
		if len(linestrings) == 0 {
			return nil
		}
		union := g.LineMerge(linestrings)
		for _, l := range union {
			g.DestroyLater(l)
		}
		return union
	} else if geomType == "Point" {
		if len(geoms) >= 1 {
			for _, p := range geoms {
				g.DestroyLater(p)
			}
			return geoms[0:1]
		}
		return nil
	} else {
		panic("unexpected geometry type" + geomType)
	}
}
Пример #4
0
func LineString(g *geos.Geos, nodes []element.Node) (*geos.Geom, error) {
	nodes = unduplicateNodes(nodes)
	if len(nodes) < 2 {
		return nil, ErrorOneNodeWay
	}

	coordSeq, err := g.CreateCoordSeq(uint32(len(nodes)), 2)
	if err != nil {
		return nil, err
	}
	// coordSeq inherited by LineString
	for i, nd := range nodes {
		coordSeq.SetXY(g, uint32(i), nd.Long, nd.Lat)
	}
	geom, err := coordSeq.AsLineString(g)
	if err != nil {
		// coordSeq gets Destroy by GEOS
		return nil, err
	}
	g.DestroyLater(geom)
	return geom, nil
}